Leaked CCTV footage shows the portly Kim being approached by two women who appear to put something in his face.
Moments later he is seen asking for help from airport staff, who direct him to a clinic.
Malaysian police said he suffered a seizure and died before he reached hospital.
An autopsy has ruled out heart failure, with investigators focusing on the theory that a toxin was applied to his face, in what South Korea has insisted was a targeted assassination.
